Many farmers are having a hard time of it these days, at least by comparison with the prosperity the successful ones enjoyed a few years ago.

But ironically, much of what they are producing - at a cost greater than they can sell it for - is not especially good for consumers.

Put simply, Britons eat too much meat and processed food, and too many dairy products. Our healthiest diet was during the difficult days of the Second World War.

Mediterraneans know best

Fatty and salty foods are linked with heart disease, and the modern, refined diet goes hand in hand with an upsurge in many forms of cancer.

There is a growing body of evidence now to suggest that one of the healthiest ways of eating is that which has developed around the shores of the Mediterranean - olive oil, pasta and pulses, fresh fruit and vegetables.

Milk and dairy products are fine in moderation...

There is little sign of a wholesale switch towards a Mediterranean diet in the UK, and it would require a cultural revolution to make it happen - a revolution embracing changes in patterns of living and a rejection of many products of the food industry.

It would need a rediscovery of the worth of preparing and cooking fresh food rather than relying on "convenience" products.

But the rewards could be great. Doctors say that the consumption of vegetables and fruit in the United Kingdom is less than half that in Mediterranean countries.

Yet it is those same vegetables and fruit that are most effective in providing protection against most of the commonest cancers.

Little change

A Cambridge university study in 1998 estimated that up to 80% of all breast and bowel cancers could be prevented if people improved their eating habits.

But for all the warnings that everyone should eat five portions of fruit or vegetables daily, few people appear to be changing their habits.

. . . and a lot of meat can be damaging

If ever there were a mass move towards the sort of diet nutritionists recommend, it would have profound consequences not just for farmers themselves, but for wildlife and landscapes as well.

There would be no need for the rearing on an industrial scale of cattle, sheep, pigs and poultry, for the provision of food for them and the disposal of their wastes.

In the lowlands, there might be little problem, because it would free thousands of acres for arable production.

But in the uplands, places like the Pennines, much of Wales, and the moorlands of south-west England, the land is good for little but sheep.

Products not needed

If you stop farming sheep there, you stop grazing the land, and a different sort of countryside would gradually emerge, scrub taking over from turf, changing the mix of species that could live there.

The real crisis of farming is that much of what we expect it to produce is food that we would be better off without.

Farmers are losing. So is the environment. And so are we all.